Rotary mowers comprise generally a mower deck, a rotating blade assembly under the deck, and a driveline connecting the blade assembly to a rotating power source, typically the power take off of a tractor to which the mower is mounted or connected by a hitch for towing.
The mower deck comprises a frame that provides the skeleton of the deck. Brackets, hitches, and the like for mounting or towing the mower are attached to a front member the frame, and wheels may be mounted to the frame at various locations to support the deck for travel along the ground. The driveline typically includes a gear box or a hydraulic motor mounted on top of a central frame member, and a shaft extending downward through the center of the deck. The blade assembly is then mounted to the shaft under the deck.
A skin of relatively thin metal covers the frame and provides the finished top side of the deck, and generally extends downward along the sides of the deck. The skin encloses the blade assembly and maintains the material being cut under the deck where same may be contacted multiple times and thus be cut into small pieces, which is generally desired. The skin also prevents material, including rocks and like hazardous objects, from being thrown upward or laterally by the rotating blades.
The rapidly rotating blades commonly strike rocks and like objects at high speed, throwing the objects and also sometimes bending the blades. It is also therefore common to provide a blade ring that extends downward from the top of the deck above the circular path of the blades. The ring prevents bent blades from striking the skin on the top of the deck and damaging the skin. Many of these thrown objects however are thrown upward and strike the skin of the deck such that after a relatively short period of usage, depending on the conditions of use and terrain being cut, the skin of a mower deck is often badly dented or even punctured, and is unsightly. The paint on the skin is damaged such that rust and corrosion rapidly occur, and debris more readily gathers on the top of the skin and is difficult to clean off.
For this reason some manufacturers provide a second lower skin welded to the frame some distance under the upper skin. Thus objects thrown by the blades strike the bottom skin, causing dents or punctures, while the top skin remains relatively unscathed. This second skin however adds significantly to the cost of the mower, putting the manufacturer at a price disadvantage over other mowers. The manufacturer could offer the lower skin as an option, however that can significantly increase inventory costs as the manufacturer and distribution network must carry both mowers. Since rotary mowers are typically available in a variety of sizes, the cost can be prohibitive.